Wednesday, 8 November 2017

'Missing Link' in Abiogenesis Found!

Scientists find potential 'missing link' in chemistry that led to life on Earth

You know, sometimes I get carried away and fantasise about creationist frauds like Ham, Comfort and Hovind hearing the tune Aproaching Menace by Neil Richardson as they read yet another scientific paper showing how science is closing in on one of their sacred dogmas - that only God can create life.

But then I come back to reality and remember that they don't do science and evidence, so none of this makes any difference to them. They'll still claim it's impossible, knowing they can rely on their willing dupes not to check just in case.

Only three days ago I reported here on the work of a team from the Georgia Institute of Technology, Atlanta, GA, USA who are homing in on one of the pre-biotic precursors of one of the fundamental cell processes. Just a day later we had this paper published in Nature Chemistry showing how another fundamental process could similarly have arisen pre-biotically. The process is that of phosphorylation, i.e, adding a phosphate group to three key components of cells.

The three components are:
  • short strands of nucleotides to store genetic information
  • short chains of amino acids (peptides) to do the main work of cells
  • lipids to form encapsulating structures such as cell walls

The problem was that there did not seem to be a single phosphorylating agent capable of performing these key functions. Other researchers have proposed different phosphorylating agents for each process, which is not in itself a major problem. The problem is that these each depends on different reaction conditions. Clearly, not a good solution.

That problem may now have been solved. Scientists led by associate professor of chemistry, Ramanarayanan Krishnamurthy, of The Scripps Research Institute (TSRI) believe they have identified just such a chemical, diamidophosphate (DAP).

Prebiotic phosphorylation of (pre)biological substrates under aqueous conditions is a critical step in the origins of life. Previous investigations have had limited success and/or require unique environments that are incompatible with subsequent generation of the corresponding oligomers or higher-order structures. Here, we demonstrate that diamidophosphate (DAP)—a plausible prebiotic agent produced from trimetaphosphate—efficiently (amido)phosphorylates a wide variety of (pre)biological building blocks (nucleosides/tides, amino acids and lipid precursors) under aqueous (solution/paste) conditions, without the need for a condensing agent. Significantly, higher-order structures (oligonucleotides, peptides and liposomes) are formed under the same phosphorylation reaction conditions. This plausible prebiotic phosphorylation process under similar reaction conditions could enable the systems chemistry of the three classes of (pre)biologically relevant molecules and their oligomers, in a single-pot aqueous environment.

The Scripps team have shown that:
  • DAP can phosphorylate each of the four nucleoside building blocks of RNA in water. In the presence of the catalyst imidazole, a simple organic molecule that could have been present on early Earth, it can build short RNA-like chains from these phosphorylated nucleosides.
  • They have also shown that DAP in water with imidazole can phosphorylate glycerol and fatty acids and build these into small phospho-lipid capsules called vesicles, the primitive beginnings of cell membranes.
  • Lastly DAP in water can phosphorylate the amino acids glycine, aspartic acid and glutamic acid, and help build these into short peptides.

And not just that, but the team have also found that DAP phosphorylates via the same basic chemical reaction - breaking a phosphorus-nitrogen bond - as do the protein kinases that are ubiquitous to present-day cells. DAP phosphorylation chemistry closely resembles what is seen in the reactions at the heart of every cell's metabolic cycle.

So, that gap, so beloved of creationists and in which they believe their god will, unlike with every other gap that science has closed, be found to reside, gets ever yet smaller. The gap of 'impossible without special God Magic' abiogenesis, so often trotted out to challenge science to explain, as though not having an answer yet means none is possible, is slowly but surely closing. The question is, what will be waved next as irrefutable 'proof' of [insert god of your choice]?

Cue, Aproaching Menace.

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1 comment :

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